The overall objective of the Pulmonary Infection and Inflammation Core is to provide small animal aerosol challenge models that support the research, career development, and developmental projects of the RCE. This Core brings together scientists with extensive experience in studying the molecular and cellular immunology and pathology of the lungs using aerosol challenge models in normal and genetically altered animals. The Core will provide state-of-the-art technical support, facilities, and collaborative expertise. The Specific Aims of the Core are to: 1. Provide aerosol challenge systems suitable for exposing mice, rats, guinea pigs, or rabbits to aerosols composed of live bacteria, lipopolysaccharide, antigenic proteins, or immunomodulators. 2. Provide investigators with specimens harvested at specific time points after aerosol challenge to permit study of bacterial and host responses to the infection or inflammatory stimulus. 3. Provide histopathologic and multiplex protein analyses of tissue specimens harvested in these experiments and in other studies performed by RCE investigators, to facilitate investigation of inflammatory and immune responses in the lungs. 4. Provide transgenic mice in which one or more host defense components have been altered to test their role in the pathogenesis of the infection.